Flash chromatography on cartridges for the separation of plant extracts: Rules for the selection of chromatographic conditions and comparison with medium pressure liquid chromatography

Empirical rules for the selection of chromatographic conditions on flash chromatography cartridges were developed, with an emphasis on gradient mode. These rules were then tested with separation of extracts from important medicinal plants including Curcuma xanthorrhiza, Piper nigrum and Salvia milthiorrhiza. Sepacore® cartridges enabled a good separation of compounds with a broad range of polarity, as typically found in plant extracts. The chromatographic resolution remained, however, lower than that achieved on classical columns packed with material of smaller particle size. For poorly soluble extracts, solid introduction gave better results than liquid injection.     

多媒体课件制作工具探讨分析

本文主要探讨常用的几种课件制作工具,并分析各软件的优缺点以及其应用的人群和使用场合。     

弧齿锥齿轮齿面闪温分布特性分析

在Blok闪温公式的基础上,计算混合弹流润滑下的齿面平均摩擦因数,修正了公式中的齿面平均摩擦因数,提高了计算精度。同时,通过计算弧齿锥齿轮沿齿面啮合点的切向速度、赫兹接触带半宽和载荷分配系数,提出了混合弹流润滑下弧齿锥齿轮沿接触轨迹和全齿面的闪温公式。经算例分析表明,非正交弧齿锥齿轮副沿接触轨迹闪温的最大值位于啮出轨迹中部,全齿面闪温的最大值在大轮节锥与齿根之间的齿面中部,这些部位最容易发生胶合。     

Structural studies on soil nitrogen by Curie-point pyrolysis — gas chromatography/mass spectrometry with nitrogen-selective detection

Curie-point pyrolysis-gas chromatography mass spectrometry with N-selective detection was used to characterize the structure of organic N compounds in four mineral soils. The technique was found suitable for the fast, sensitive, and highly specific identification of N-containing pyrolysis products from whole soils with total N contents between 0.08 and 0.46%. In order to optimize the methodology, one agricultural soil was pyrolyzed at final temperatures of 573, 773, and 973 K. Almost no chemical alterations to identifiable pyrolysis products were observed when the final pyrolysis temperature was increased from 573 to 973 K. More than 50 N-containing pyrolysis products were identified, and were divided into compound classes chracterized by specific molecular-chemical structures. These included pyrroles, imidazoles, pyrazoles, pyridines, pyrimidines, pyrazines, indoles, quinolines, N derivatives of benzene, alkyl nitriles, and aliphatic amines. Three additional soil samples different in origin and N content were analyzed at 773 K and each showed a specific thermosensitive N-selective chromatogram. Many N-containing pyrolysis products were identified in all samples, which indicated general qualitative regularities in the thermal release of N-containing pyrolysis products from the four soils. In the pyrolyzates of the investigated soils a number of compounds were identified, which is usually not detectable in pyrolysis-gas chromatography spectrometry analyses with N-selective detection of plants and microorganisms. Among these were N derivatives of benzene and long-chain alkyl nitriles, which appear to be soil-specific and suggest significant transformations of organic N in soils. Thus, our results contribute to a better understanding of the molecular-chemical structure of unknown N.     

基于Flash的鱼类标本展示技术

通过简易的悬挂和转动装置,对鱼体进行多角度连续拍摄,结合图像处理和Flash Action Script技术,实现鱼类标本影像模型的建模和制作,并利用网站发布到互联网。该技术方法简单,拓展性好,为教育教学和科研提供新的方法和手段。     

探讨案例教学法在Flash动画制作课程中的应用

中高职院校以就业为导向,开设了《Flash动画制作》课程。该课程与就业联系比较紧密,实践性很强。研究提出了传统的教学方法已经不能够适应该课程的教学,提出有必要在Flash教学中引入案例教学。     

用Flash实现数据结构算法的动态演示

数据结构是计算机专业的重要课程,其中涉及到大量复杂的算法,而算法恰恰是数据结构教学中的难点。本文阐述借助Flash软件如何将这些抽象而复杂的算法形象的表达出来,从而实现数据结构算法的动态演示。     

大学物理多媒体教学课件制作研究

大学物理课程是高等学校理工科各专业学生一门重要的必修基础课，包括课堂教学和实验教学两个环节。多媒体教学信息量大，覆盖面广，能使媒体资料得到充分共享。本文首先介绍了用PowerPoint、VB、Authorware、Flash综合设计课件的方法，然后介绍了用VB等设计的大学物理多媒体教学课件的总体方法和具体实现。大学物理多媒体教学课件包括：课前提问、进入课堂、布置作业、课后自测、教学大纲、教学进度、实验内容、实验视频、素材演示功能模块。     

大学物理多媒体教学课件制作研究

大学物理课程是高等学校理工科各专业学生一门重要的必修基础课,包括课堂教学和实验教学两个环节.多媒体教学信息量大,覆盖面广,能使媒体资料得到充分共享.本文首先介绍了用PowerPoint、VB、Authorware、Flash综合设计课件的方法,然后介绍了用VB等设计的大学物理多媒体教学课件的总体方法和具体实现.大学物理多媒体教学课件包括:课.前提问、进入课堂、布置作业、课后自测、教学大纲、教学进度、实验内容、实验视频、素材演示功能模块.     

Authorware中动态弹出式菜单的编程

介绍了在Authorware中利用事件交互,将用Flash制作的动态弹出式菜单应用于Authorware程序中的详细实现方法。由于只需修改与该菜单关联的外部XML文档即可改变菜单的菜单项及色彩效果等参数,故可以很方便地将完成的程序移植到其他程序中,大大提高了课件制作时的效率,因而有较大的应用价值。